Catalytic conversions



Jan. 1, 1946. w. P. GAGE CATALYTIC CONVERSIONS Original Filed Sept. 20, 1941.

lnvenkir: William P. Gage 6g his A'H'ornzq- M Patented Jam 1, 1946 2,392,284 7 CATALYTIC CONVERSIONS William P. Gage, San Anselmo, CaliL, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Original application September 20, 1941, Serial No. 411,687. Divided and this application July 24, 1944, Serial No. 546,257

13 Claims.

This invention relates to the execution of catalytic hydrocarbon conversions with the aid of normally gaseous promoters. A particular aspect of the invention relates to the catalytic isomerization of hydrocarbons with the aid of hydrogen process economically feasible. The use of a normally gaseous promoter involves added operative steps such as, for example, the separation of the promoter from the reaction products, its return to the reaction zone, etc., and the manner in which these steps are executed influences markedly the efliciency of the process. Another vital factor in these processes is the cost of the promoter. The normally gaseous promoters must generally be used in the anhydrous form, and since they often are not readily available in large quantities in this form, or, when available, are generally relatively costly, it is essential to efficient operation of the process that they be recovered substantially completely with a minimum of operative steps from gaseous materials eliminated from the system.

It is an object of the present invention to provide an improved process for the execution of catalytic hydrocarbon conversions with the aid f normally gaseous promoters. A further object of the invention is the provision of an improved process whereby hydrocarbons can be catalytically isomerized in the presence of hydrogen hal- Y ide promoters with substantially increased efliciency.

In accordance with the process of the invention, reactants comprising, for example, a hydrocarbon to be converted and an added hydrogen halide are contacted at conversion conditions with a suitable catalyst in a reaction zone. A. liquid hydrocarbon fraction, preferably obtained within the system, is added to the products leaving the reaction zone. The resulting mixed stream is cooled and' passed into an accumulating zone. The amount of liquid hydrocarbons thus to the products leaving the reaction zone and the degree to which the resulting mixed stream is further cooled are controlled to effect the condensation of vaporized reaction products and, also, the dissolving of substantially all of the hydrogen halide present. A liquid stream comprising hydrocarbon reaction products containing dissolved hydrogen halide is passed from the accumulating zone to a fractionating zone wherein a gaseous fraction comprising the hydrogen halide promoter is separated and recycled to the reaction zone. The part of the normally gaseous fraction in excess of that immediately required in the reaction zone is introduced into the mixed stream of reaction products and added liquid by drocarbon fraction passing into the accumulating zone. Fixed gases accumulating within the system and unavoidably including a certain amount of the gaseous promoter are removed from the accumulating zone and scrubbed with the liquid hydrocarbon fraction which is to be added to the efliuence of the reaction zone.

The process of the invention is applicable to a wide variety of processes wherein catalytic conversions, particularly hydrocarbon conversions, are executed with the aid of normally gaseous promoters. However, for the purpose oi simplicity in setting forth more fully the nature of the invention, it will be described in detail hereinafter in its application to the isomerization of hydrocarbons with the aid of an aluminum halide catalyst in the presence of a hydrogen halide promoter. The invention will be more clearly understood from the following detailed description thereof, read in connection with the accompanying drawing, which forms a part of this disclosure, and in which the single figure is a more or less diagrammatic elevational view of a form of ap= paratus suitable for executing the process of the invention.

Referring to the drawing, an isomerizable hydrocarbon such as, for example, normal butane,

is drawn from an outside source and forced by means of pump in through line H into a drying zone. The drying zone may consist of a plurality of chambers i2 containing a suitabl dehydrating agent such as, for example, alumina, calcium chloride, or the like. From driers i2, the dried stream is passed through lines l3 and I4, into a reaction zone. The reaction zone maycomprise, for example, an enlarged reaction chamber and /or a plurality of reaction tubes. In the apparatus shown in the drawing, the reactor l5 comprises a plurality of tubes positioned in a vessel enabling the maintenance of a heating or cooling fluid in direct contact with the external surface of the tubes. Suitable header arrangements are comprised within the vessel permitting the passage of fluid reactants in parallel flow through the plurality ofreaction tubes. Although but one such reactor is shown in the drawing, a greater number, connected in series and/or in parallel, may be used. 7 7

An isomerization catalyst, for example an'aluminum halide on a suitable support material, such rogen hal de such as hydrogen chloride, obtained ably obtained within the system of the process. Thus, a cooled liquid butane traction, separated from the reaction products within the system as described more fully below, is introduced through line 24 into line 20. The amount of the butane fraction so introduced into line and the extent of cooling eflected inooolers Hand 23 are controlledto efiect not only the condensation of butane vapors prior to entry of the stream into accumulator 2|, but to bring about the solution or substantially all of the hydrogen chloride present in line 20. The amount of cooling required will vary with variations in operating conditions and notably with variations in the-amount oi' hydrogen chloride entering line 20. When the hydro gen chloride content 0! the mixture in accumulato'r 2!, consisting essentially of butanes and hydrogen chloride, amounts to, tor example, about 5.5 mol per cent, a temperature. or approximately from an outside source, or recycled from within I thesystem as described more fully below, is passed thro eh line H) into line H. The amount of hydroge chloride. introduced into the s stem may vary in accordance with the nature of the charge, catalyst composition, and operating conditions. Thus, in the isomerization oi butane, the amount of hydrogen chloride introduced into the system may range from about 0.3% to about 10% of the butane char e and even hi her if des red.

The cond tions of temperature and pressure ma ntained in the react on zone may vary widely with the nature of the charge and the particular catalyst used. Thus. in the vapor phase isomerization of butane, a temperature in the approximate range of, for example, 50 C. to 200 0., preferably in the approximate'ranze of 90 C. to 150 C., and a pressure of about 140 pounds have been found suitable to permit solution of substantially all of the hydrogen chloride.

. Liquid comprising butanes and dissolved hydro gen chloride is withdrawn from accumulator 2| and forced by means of pump 25 through line '26 into a stripping column 21. Within stripping col-' umn 21, a gaseous fraction comprising hydrogen chloride is separated from a liquid fraction comprising butanes. Cooling means such as, for example, a closed cooling coil 28 is positioned in the upper part or the column 21 and heating means such as, for example, a' reboiler or a closed heating coil 29 is positioned in the lower part thereof to aid in effecting the desired separation. A high Pressure, for example in excess of about 300 pounds, may be maintained within stripping column 27. The gaseous fraction is withdrawn over- C., may be used. The o eration may be executed at any pressure at which butane may be maintained in the vapor phase. for example in the approximate range of from to 500 pounds.

Within reactor 55, the conversion of butane to isobutane is effected. Products comprising isobutane, unconverted butane, and hydrogen chloride are withdrawn from reactor l5 and passed through line 20 to an accumulator 2i. In passing through line 28, the reaction products are cooled by in-' direct heat exchange with the charge in indirect heat exchanger 57 and by passage through suitable coolers 22 and 23. When, under the pressure conditions usually employed, the products from the reaction zone are cooled .Iust sumciently to condense the butanes contained therein, at least a substantial part of the normally gtlseous promoter will remain'in the gaseous phase. rate flows of gaseous and liquid materials must then be passed from accumulator 2| to the fract'ionating system of the process. The use of 0001- Sepahead-from stripper 27 and passed through line it to the reactor l5.

Generallythe amount of hydrogen chloride introduced intothe reaction zone; will fluctuate throughout the operation. Therefore, the amount of hydrogen chloride liberated by stripping col- .the reactor I5 is passed therefrom through line ing temperatures sufdciently low and/or pressures sumciently high to bring about the solution of at least a substantial part of the hydrogen chloride in the amount of hydrocarbons normally obtained from the reaction zone, to thereby enable the passage of buta single stream of materials from accumulator 2| to the iractionating system, although within the scope of the present invention,

is not always economically desirable. In one form of carrying out the process of the invention, solution of substantially all of the hydrogen chloride in the liquid within accumulator 2| is made possible at more moderate conditions of temperature umn 2? often will exceed that immediately re-. quird by reactor l5. These fluctuations are, however, generally not so great as to justify the added expense of piping, compression, hydrogen chloride loss, and'risk of contaminating the hydrogen chloride entailed in passing and temporarily maintaining this excess in separate gas storage means. In the process of the invention, the amount of'hydrogen chloride flowing through line IS in excess of that immediately required by 30, controlled by valve 3 I into line 20; the amount of promoter in excess of that immediately required thus being dissolved in the butane stream entering accumulator II. It is seen that accumulator 2i functions as a storage means within the system for the hydrogen chloride in'excess of that immediately needed by the reactor l5.

Hydrogen chloride may be introduced into the system as required from an outside source through line 33, controlled by valve 34.

- Liquid comprising normaland isobutane is withdrawn from the lower part of stripping column 21 and passed through line 35, controlled by valve 36, into fractionator 31. A controlled amount of the liquid flowing-through line 35 is passed through valved line 26, wherein it is cooled by passage through heat exchanger l6, into-line butane is separated'trom a liquidiraction comprising normal butane. The vapor fraction is withdrawn irom the top of iractionator I1 and passed through line 38 and cooler 39, into accumulator 40. Liquid comprising isobutane is withdrawn irom accumulator 40 through line 4!,

controlled by valve 42, as thermal product. A

part the liquid withdrawn from accumulator 40 is forced by means of pump 43 through line 44 as reflux to the top. of fractionator 31. Liquid comprising normal butane is withdrawn from the lower part of fractionator 31 through line 45,

controlled by valve 48, and eliminated from the system. At least a partof the normal butane withdrawn from fractionator 31, is forced by means of pump 41 into line H. A heating means such as, for example, a reboiler or closed heating coil 32' is placed in the lower part of fractionator 31 to aid in the desired fractionation therein.

' During the course of the operation, a certain amount of normally gaseous material comprising, tor example, hydrogen, will accumulate in the system as a result 01' undesired side reactions and must be removed in part or in its entirety from the system. This gas will comprise a considerable amount of the anhydroushydrogen chloride promoter, loss of which would seriously afiect the economy of a' large-scale process. In the process ofthe invention this hydrogen chloride is recovwithin the system'ior hydrogen chloride recovered from fixed gases and for the excess hydrogen chloride given off by stripping column 21.

The invention has been described in detail in its application'to the vapor phase isomerization of butane. vention is in no wise limited to the isomerization of this particular hydrocarbon. Thus, by the inclusion in the charge of suitable agents such as,

ered from the gas efliciently, and at little extra cost, within the system of the process. This is accomplished by continuously or periodically withdrawing gaseous material from accumulator 2| and' forcing it with the aid of compressor .50 through line 5 l,- intothe lower part of an absorber 52. A part or all of the butane stream flowing through line 24 is passed through line 53, controlled by valve 54, as the absorbing medium, to the upper' part of absorber 52. A cooler is positioned inline 53 to permit the cooling of the absorbing medium. Fixed gases substantially free of hydrogen chloride are eliminated from the system through valved line 55. The butane stream, comprising absorbed hydrogen chloride,

for example, hydrogen, isobutane, etc., capable of suppressing undesirable side reactions, the vapor phase process as described herein may be advantageously employed for the isomerization of higher saturated hydrocarbons such as the pentanes, hexanes, methyl cyclopentane, etc.

By substituting for the reactor I 5 and the catalyst described above a reactor and catalyst enabling isomerization in the liquid phase, the process of the invention may be applied with advantage to the liquid phase isomerization of hydrocarbons, such as, for example, saturated hydrocarbons having from four to nine carbon atoms and comprising pentane', nfeth'yl, cyclopentane, dimethyl cyclopentane, the hexanes, methyl cyclohexane, heptane and similar straightor branched-chain parafllnic and naphthenic hydrocarbons. Any suitable liquid phase isomerization catalyst, such .as, for example, a molten salt mixture comprising a hydrogen halide may be used. The hydrocarbons treated in the process f the invention need not bepure individual compounds but may be :5 mlxtureof more than one hydrois passed from the absorber 52 through valved line 58, into line 24; the recovered hydrogen chloride thus-being returned throug line to accumulator II. If desired, at least a part of the butane stream comprising absorbed HCl leaving absorber 32 may be combined-by means not shown in the drawing, with reaction products flowing to colmm: 21, at a point beyond line 20. A valved line 51 is provided to permit the passage of gaseous carbon.

Although the invention can be applied with particular advantage to the isomerization of hydrocarbons, it is not intended to limit its scope to the execution of this particular hydrocarbon reaction. The invention may suitably be applied to the execution of a wide variety of catalytic hydrocarbon conversions, both in the liquid and vapor phase, wherein a normally gaseous promoter or a normally gaseous catalyst material, capable of being absorbed by, or dissolved in the charge, or a fraction of the Products produced within the system is used. The invention can be applied with advantage, for example, to catalytic hydrocarbon conversions such as cracking,

improved emciency. This improved eiliciency is attained not only by a reduction in operating cost obtained by the advantages comprising those specifically mentioned above, but as a result of other added advantages, such as extreme ease in maintaining optimum operating conditions in all phases or the process. These added advantages are attained, at least to a, substantial degree, by the recycling of butanes from stripping column 21 to line 10. The resulting increase in the availpolymerization, alkylation, reversion, and the like, wherein catalysts such as those of the Friedel-Craits typ or any other type, can be used in the presence of hydrogen halide promoters.

This application is a division of co-pending application, Serial No. 411,687, filed September I claim as my invention:

1. In a process wherein butane is isomerized by passage in admixture with hydrogen chloride at isomerizing conditions through a reaction zone containing an isomerization catalyst, reaction ,products are passed through an accumulating eiliuence from the reaction zone, bringing said fixed gases into intimate contact with an absorbing medium in an absorber thereby dissolving hydrogen chloride in said absorbing medium, passing a part ofaaid liquid fraction to the ab- It is'to be understood that the insorber as the absorbing medium, combining the hydrogen chloride from the accumulating zone to the fractionating zone.

2. In a hydrocarbon conversion process wherein hydrocarbons are converted by passage in admixture with a hydrogen halide at conversion conditions through a catalyst-containing reaction zone, reaction products are passed through an accumulating zone to a fractionating zone, fixed gases comprising hydrogen halide are eliminated from the accumulating zone, and a normally gaseous fraction comprising hydrogen halide is separated from a liquid fraction comprising hy-, drocarbons in the fractionating zone, the combination of steps which comprises recycling 2. part of said gaseous fraction to the reaction zone, combining the remainder of said gaseous fraction with the efliuence from the reaction zone, bringingsaid fixed gases into intimate contact with an absorbing medium in an absorber th'ereby dissolving hydrogen halide in said absorbing me-' dium, passing a part of said liquid fraction-to the absorber as the absorbing medium, combining the enriched absorbing medium with the eiiiuence from the reaction zone, cooling the resulting mixed stream to a temperature sufficiently low to dissolve at least a'substantial part of the hydrogen halide present in' the hydrocarbons, passing the cooled stream to the accumulating zone, and passing liquid comprising dissolved hydrogen halide from the accumulating zone to the fractionating zone.

3. In a hydrocarbon conversion process wherein hydrocarbons are converted by passage in admixture with a hydrogen halide at conversion conditions through a catalyst-containing reaction zone, reaction products are passed through an accumulating zone to a fractionating zone, fixed gases comprising hydrogen halide are eliminated from the accumulating zone, and a normally gaseous fraction comprising hydrogen halide is sep-- arated from a liquid fraction comprising hydrocarbons in the fractionating zone, the combination of steps which comprises bringing said fixed gases into intimate contact with an' absorbing medium in an absorber thereby dissolving hydro gen halide in said absorbing medium, passin a part of said liquid fraction to the absorber as the absorbing medium combining the enriched absorbing medium with the eflluence from the reaction zone, cooling the resulting mixed stream to a temperature sufliciently. low to dissolve at least a substantial part of the hydrogen halide present in the hydrocarbons, passing the cooler stream to the accumulating zone, and passing liquid comprising dissolved hydrogen halide from the accumulating zone to the fractionating zone.

4. In a hydrocarbon conversion process wherein hydrocarbons are converted by passage in admixture with a hydrogen halide at conversion conditions through a catalyst-containin reaction zone, reaction products are passed through an accumulating zone to a fractionating zone, fixed gases comprising hydrogen halide are eliminated from the accumulating zone, and a normally gaseous fraction comprising hydrogen halide is separated from a liquid fraction comprising hydrocarbons in the fractionating zone, the combination of steps which comprises bringing said fixed gases into intimate contact with an absorbing medium in an absorber thereby dissolving hydrogen halide in said absorbing medium, passing a part of said liquid fraction to the absorber as the absorbing medium, and combining the enriched absorbing medium with said reaction products passed to the iractionating zone.

5. In a hydrocarbon conversion process where'- in hydrocarbons are converted by passage in admixture with a hydrogen halide at conversion conditions through a catalyst-containing reaction zone, reaction products are passed through an accumulating zone to a 'fractionating zone, fixed gases, comprising hydrogen halide are eliminated from the accumulating zone, and a normally gaseous fraction comprising hydrogen halide is separatedfrom a liquid fraction comprising hydrocarbons in the fractionating zone, the'combination of steps which comprises recycling a part of said fixed gases comprising'hydrogen halide from the accumulating zone-to the reaction zone, bringing the remainder of said fixed gases into intimate contact with an absorbing medium in an absorber thereby dissolving hydrogen halide in said absorb-' I ing medium, passing a part of said liquid fraction to the absorber as the absorbing medium, and combining the enriched absorbing medium with the eiiiuence from the reaction zone.

6. In a hydrocarbon conversion process wherein hydrocarbons are converted by passage in admixture with a hydrogen halide at conversion conditions through a catalyst-containing reaction zone, reaction products are passed to a fractionating zone, and a normally gaseous fraction comprising hydrogen halide is separated from a liquid fraction comprising hydrocarbons in the fractionating zone, the combination of steps which comprises recycling a part of said gaseous fraction to the reaction zone, combining the remainder of said-gaseous fraction and a part of'said liquid fraction with the efliuence from the reaction zone,

' zone, reaction products are passed to a fractionating zone, and a normally gaseous fraction comprising hydrogen halide is separated from a liquid fraction comprising hydrocarbons in the fractionating zone, the combination of steps which comprises recycling a part of said gaseous fraction to the reaction zone, combining the remainder of said'gaseous fraction with the eflluence from the reaction zone, cooling the resulting mixed stream to a temperature sufiiciently low to vdissolve at least a substantial part of the hydrogen halide present in the hydrocarbons, passing the cooled stream to an accumulating zone, and s passing liquid comprising dissolved hydrogen halide from the accumulating zone to the fractionating zone.

8. In a hydrocarbon conversion process wherein hydrocarbons are converted by contact in the vapor phase in admixture with a hydrogen halide at conversion conditions with a catalyst in a catalyst-containing reaction zone, reaction products are passed to a fractionating zone, and a normally gaseous iraction comprising hydrogen halide is separated from a liquid traction comprising hydrocarbons in'the fractionating zone, the combination of steps which comprises first separating said reaction products from the catalyst prior to any substantial condensation thereof, cooling said separated reaction products to condense at least a substantial'part of. the hydrocarbon content thereof, combining a part of said liquid fraction from said fraotionating zone with said cooled reaction products, further cooling the resulting mixed streamto a temperature sumciently low to dissolve at least a substantial part of the hydrogen halide present in-the reaction products in the hydroyarbons, passing the cooled mixed stream to an accumulating zone, separately withdrawing gases comprising hydrogen halide and liquid comprising hydrocarbons containing dissolved hydrogen halide from the accumulating zone, and passing said liquid from the accumulathalide is separated from a liquid traction com;

prising the hydrocarbon isomerizate in'the fracmedium, and combining the enriched absorbing medium with the said reaction products passed to the fractionating zone. I

11. In a process wherein saturated isomerizable hydrocarbons .are isomerized by passage in admixture with a hydrogen halide at isomerizing conditions through a reaction zone containing an isomerization catalyst, isomerization products are erizate to the absorber as the absorbing medifractionating zone.-

tionating zone, the combination of steps which comprises bringing said fixed gases into intimate contact with an absorbing medium in an absorber, thereby dissolving,hydrogen chloride in said absorbing medium, passing a part of said liquid fraction comprising said hydrocarbon isomerizate to the absorber as the absorbing medi-' um, combining the enriched absorbing medium with'the eflluence from the reaction zone, cooling the resulting mixed stream to a temperature sufliciently low to dissolve at least a substantial part of the hydrogen halide present in the hydrocarbons, passing the cooled stream to the accumulating zone, and passing liquid comprising dissolved um, and combining the enriched absorbing mediuin with said reaction productspassed'to the 12. In a process wherein butane is isomerized by passage in admixture with hydrogen chloride at isomerizing conditions through a reaction zone containing an isomerization catalyst, isomerization products are passed through an accumulating zone to a tractionating zone, fixed gases com prising hydrogen chloride are eliminated from the accumulating zone and Ia normally gaseous iraction'comprising hydrogen' chloride is sepaand unreacted normal butane in the iractionat ing zone, the combination of steps which comprises bringing said fixed gases into intimate contact with an absorbing medium in an absorber, thereby dissolving hydrogen chloride in saidabsorbing medium, passing a part of said liquid fraction comprising said'jisobutane and unreacted normal butane to the absorber as the absorbing medium, and passing the enriched absorbing mehydrogen halide from the accumulating zone to the iractionating zone.

10. In a process wherein butane is isomerized by passage in'admixture with hydrogen chloride at isomerizing conditions through a reaction zone containing an isomerization catalyst, isomeriza- -tion products are passed through an accumulate ing zone to a fractionating zone, fixed gases comprising hydrogen chloride are eliminated from normal butane to the absorber as the absorbing steps which comprises bringing said fixed gases into intimate contact with an absorbing medium, in an absorber, thereby dissolving hydrogen halide 'in said absorbing medium, passing a part of said liquad fraction comprising said hydrocarbon isomerizate to the absorber as the absorbing medium, and passing the enriched absorbing medium from the absorber to the tractionating zone,

' wnmnm r. anon. 

